Can someone describe the sound of KEF IQ30's ?

I'm so hesitant to buy used speakers

your polks are better than fine.

If you "must" buy some new speakers to replace your Polks, and want to stay "south" of the $500 line, then I would recommend that you take a listen to the Energy RC-10s.

Also, since you mentioned that you like the NHT Classic Threes, you might keep checking to see if your dealer is going to reduce it's price. NHT is closing it's doors on March 31, so there could be some "good sales" on their remaining speakers, as most dealers will probably be dropping the line. Kind of sad to see them go, and hopefully wiil see then (NHT) on the "other side".

Btw,

I listen to both the Energy RC-10s and NHTs Classic Three through a Denon system and enjoyed the sound of both, although I must say my preference was for the Energy RC-10. Definely think either one would be a step up from the Polk Rti28. Actually IMHO both the Energy and the NHT compared well with the Polk Lsi7.

I will have to check Energy. They seem to have some good speakers at lower price points. The Polks are fine..I'm just noticing things of late. Also, I plan on keeping them for spares (when I get a house) so I could always go back. I thought that maybe the KEF's may be a good, lower cost alternative to the B&W 685. I'll do searches on the Energys